1. Field of the Invention
The present invention relates to a load drive device having a short-circuit protection function.
2. Descriptions of the Related Arts
When, in general, a drive signal is generated from a control circuit in a load drive device which drives an electric load such as a solenoid coil, an output transistor is turned on in response to the drive signal, and a power source voltage is applied to the load via the output transistor, that is, for example, via the emitter and collector path of the output transistor. The application of the voltage to the load is detected by a voltage detection circuit, and a detection result is supplied to the control circuit. For example, in the event that the load is directly short-circuited or a harness to the load is short-circuited, the power source voltage will be directly applied to the output transistor in the turning-on state, so that an over-current exceeding a rated maximum current will flow through the emitter and collector path of the output transistor. At this time, since no detection result for the application voltage to the load can be obtained, the control circuit stops the generation of the drive signal as an indication of occurrence of an accident, when no detection result for the application voltage to the load can be obtained by the voltage detection circuit during producing the drive signal. Thus, it can be prevented that the over-current flows continuously through the output transistor.